That's what happening when you're not playing other branches and build theories (or better to say generate them) from the head or based on some assumptions which is based on another assumptions with zero grounds
Lana & Jonathan just assumed that their fathers could also did drugs when they was younger or in college. That's all. And if they are - Buddy & Rox was a kids at that time.
Geoff's character is a desperate father, who still feels guilty and grief, even though 10+- years had past since his daughter death. He found relief in alcohol and this is going more and more bad with each year. You can find out THIS if you'd play Jill or Bella's branches.
Buddy is Rox's brother and Quinn's uncle.
Quinn was taken to an orphanage shortly after her father's death, and she soon found a foster family. She was a difficult child because of where she grew up and because she had learned some "life lessons" from her father. Shortly after she was adopted, when she was in high school, she ran away back to Buddy. That's how her "career" began, he wouldn't let her live in a drug den, but she started selling drugs. She returned to foster care, accepted her fate, and learned to pretend and "use" her foster parents. At the beginning of the episode, after a flashback with Lana, we see her talking to someone on the phone. It's one of her foster parents. She talks about Christmas, when and how she is planning to celebrate it, etc. By playing her branch you will also learn how and where she met Riona and HOW Quinn used her for years, but their friendship only strengthened and intensified, while Quinn always expected the opposite from her not understanding why she is so attracted to her. After she ends telling her story she wants MC to call her an awful person and abandon her. And there we have a choice to finally take her side or leave her. It's a split for the further Quinn/Riona paths, obviously. And an important MC's "moral" choice too.